1. Field of the Invention
The present invention relates to fishing rod stock and a method of manufacturing the rod stock. More particularly, the invention relates to a method of manufacturing tubular rod stock by winding, around a gently tapered mandrel, prepreg formed of high strength fiber impregnated with a thermosetting resin, and allowing the resin to harden. Specifically, the invention relates to a technique of determining condition of fishing rods.
2. Description of the Related Art
A conventional technique of determining condition of fishing rods is disclosed in Japanese Patent Publication Kokai No. 62-292422, for example. According to the conventional technique, a mandrel having a sharply tapered intermediate portion is used in manufacturing fishing rod stock. Completed fishing rod stock has varied bending strengths based on a difference in diameter between a tip end portion and a butt end portion thereof.
Where, as in the prior art, the mandrel used includes a sharply tapered intermediate portion, a desired condition of fishing rods is achieved relatively reliably. However, a single sheet of prepreg may be creased in a region corresponding to the intermediate portion of the mandrel. It is difficult to apply a suitable pressure uniformly over the prepreg being wound. The prior art method has room for improvement with respect to manufacturing efficiency.
On the other hand, a fishing rod used for catching relatively large fish should be flexed in arcuate form with a bending force distributed throughout the rod when drawing a fish. This allows the angler to draw and land a fish with ease by using elasticity of the rod. However, a fishing rod formed of the rod stock having varied diameters as noted above includes an intermediate position presenting a change in the modulus of elasticity (or a change in the modulus of section) of the rod. This results in local bending of the fishing rod, making it difficult to flex the entire rod in a large arcuate form.
Fishing rod stock may be manufactured easily by winding prepreg around a gently tapered mandrel. However, a rear end region of this fishing rod stock has insufficient flexural rigidity compared with a tip end region thereof. A fishing rod formed of prepreg having a uniform modulus of elasticity has the inconvenience of tending to bend greatly in a rear end region thereof. There is room for improvement in this respect also.